If for example there is an equal sensory signals

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Unformatted text preview: e any ight of evidence describe the probability of each is issued inNeurons cess actuevidence is sampled. If, for example, there is an equal Sensory Signals-Turing’s Weight of Evidence th f 1/10 of prior probability of either hypothesis (which was the onsidered eant that 1968; Link and Heath, 1975; Luce, 1986;the weight of assumption made in Banburismus), then Ratcliff and ce that is , implied Rouder, 1998;equal to the logarithm of the ratio of the evidence is Stone, 1960; Usher and McClelland, 2001; od, Howposterior probabilities. In this case, for a given weight er. 1979). Vickers, 1979). df the co“natural of evidence (e.g., is analogous to in Banburismus): This problem the stopping point one-dimensional ted quanlar tradeBrownian motion to a pair of barriers (Link, 1992; Ratcliff Pr(h1|m) obabilities articular and Rouder, 1998). The weight of evidence B means of the normal distribu(3) log Pr(h0|mdrift rates, (where the subscript i ) surprisal” r can be tions represent the i bans but f reward reflects B is particular motion strength).the barrier height the a constant that represents The psychometwhere m of base ric function describing the probability of correctly reachin favor of h1. For two mutually exclusive hypotheses Decision Model tion-time Figure 2. ing eitherh the is“up” r(h difference between equivalently, given) antineuron is: or “down” barrier on a Pr(h trial The weight (Pr(h favor of evidence in |m) over h the accumulated |m) or, responses of a neuron that prefers h and an 1 1 0 7). The curves depicted P computed under the condition that h is true. The thin, wavy line depicts a simulated 1 0 ihich the trajectory that represents how the weight of evidence are grow on a single trial as a function of time. The dashed line depicts the expectation lities has that prefers h (see Equation and assuming the of proportionality of relate the accumulated is exPr(h1)), at each time point. Notemightchanging the constantweight used to evidence difference (mean value) of this trajectory 100 years to the weight of evidence (see text for details) simply that the ordinate. The two insets illustrate the correspondence between the weight 1 to make of evidencepressedrule:antineuronscales i rearranges as hypothetical (normal, equivariate) probability(8) Decision neuron and the distributions of theattotal number of spikesBgenerated by the neuron and anti...
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This note was uploaded on 09/15/2011 for the course COGS 1 taught by Professor Lewis during the Spring '08 term at UCSD.

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